Fertilizer, spawning stress blamed for big fish kill in Framingham

Tuesday

Jul 31, 2007 at 12:01 AMJul 31, 2007 at 1:00 PM

The death of 500 to 800 sunfish in Framingham's Norton Pond is one of only about 20 so-called fish kills since this summer, officials said yesterday, and the single-species death signifies high stress more than pollution.

By D. Craig MacCormack

The death of 500 to 800 sunfish in Framingham's Norton Pond is one of only about 20 so-called fish kills since this summer, officials said yesterday, and the single-species death signifies high stress more than pollution.

Low oxygen levels, partly because of invasive plant life known as water meal, and high stress among the sunfish during their spawning season were the likely culprits in the massive deaths, which led to a strong odor in the neighborhood and a layer of green film similar to cornmeal on the pond last week.

Because the pond, the second smallest of Framingham's quintet, is surrounded by homes, a high nutrient level caused by lawn fertilizer is likely to have led to the outgrowth of water meal, officials said.

This is believed to be the first fish kill in Framingham in many years, said Conservation Agent Michele Grzenda, but the phenomenon is not uncommon across the state.

Richard Hartley, fish kill coordinator for the state Department of Fisheries and Wildlife, said there have been about 20 across the state since late spring, a number that has been consistent for several years in the 3,000 or so lakes and ponds in Massachusetts.

The fish will be left in Norton Pond to decompose and eventually be eaten, said Grzenda.

There have been no other fish kills reported this year in MetroWest, said Hartley, with the closest seen in Andover.

High temperatures "can play a role in this," said Hartley. With a heat wave marked by several days above 90 degrees, the water temperature can often approach the air temperature, he said.

Hartley is encouraged, though, to see that Framingham's fish kill, estimated to have killed 500 to 800 sunfish last week, only claimed one type of fish.

He estimated there are about a dozen types of fish in the pond.

Had the kill claimed more than one type, said Hartley, pollution of the pond would be the more likely cause.

At a time when sunfish are spawning, with nests set up along the surface of ponds and lakes, a lack of oxygen is even more likely, he said.

"This is a very stressful time for these fish and they're using up a lot of energy," said Hartley.

Grzenda expects the Conservation Commission to talk this winter about how to better deal with the water meal outbreaks in the future. The commission sent letters to the neighbors of all ponds earlier this year, warning them to be cautious about the fertilizers used on their lawns, she said.

"There are a lot of long-term solutions," said Hartley. "But sometimes you need the quick fix to get a situation under control."

Craig MacCormack of The MetroWest Daily News (Framingham, Mass.) can be reached at 508-626-4429 or cmaccorm@cnc.com.